Robin, G4DVJ, and Chris, G8LVK, have put up on their Monitor Internet website their hardware mod for the Realistic/Radio Shack DX-394 for downconversion to a 12kHz 3rd IF for DRM and other sound card DSP demodulators such as SDRadio. A beautiful piece of work it is, too, both in execution and publication, incorporating the Sat-Schneider module. They added a buffer and impedance-matched 10kHz ceramic filter.

Whether you have a DX-394 or not, have a look at their website and be inspired! It's at
http://www.monitor.co.uk/radio-mods/dx-394/dx-394.htm#mods